What happened
On 22 January 2008, a Bombardier BD-700 Global Express, registration VP-CRC, arrived at Exeter Airport for a transit stop during a flight destined for Los Angeles. The aircraft was marshalled onto a disused runway, parked facing east, approximately 150 feet from the nearest light aircraft. Due to the surface condition of the standard grass parking area, several light aircraft were parked on or near the disused runway.
Before starting the engines, the pilot assessed the potential for jet wash effects on nearby aircraft and informed the handling agent that the light aircraft should be safe as they were tied down. After starting both engines, the crew began a right-hand turn to align with the runway. To maintain this turn, a thrust setting higher than idle was necessary. During this maneuver, the jet blast from the engines struck a Cessna 152 that had been moved to a position roughly 170 feet away. The force of the exhaust lifted the tail of the Cessna 152, causing it to flip onto its back and sustain considerable damage. There were no injuries to the three crew members or the single passenger on board the large jet.
The investigation
The investigation examined the movement of the aircraft and the engine settings used during the turn. Flight data recorder analysis confirmed that the aircraft required thrust above idle to complete the turn, reaching a peak of 57% N1. The investigation also reviewed the engine manual, which provides guidance for jet exhaust flow at idle thrust but lacks specific instructions for thrust settings above idle. Additionally, the investigation noted that the Cessna 152 was not tied down at the moment of the incident, as two members of the flying club staff were holding the aircraft in place.
Findings
- The aircraft was operating at a high gross weight, necessitating higher thrust settings for taxiing and tight turns.
- The use of thrust above idle during the turn caused the jet blast to damage the light aircraft.
- The specific light aircraft involved was being held by staff rather than being secured by tie-downs at the time of the event.
- The aircraft manufacturer's manual provides no specific guidance for managing jet wash when thrust is set above idle.